LONGITUDINAL ASSESSMENT OF BLOOD PRESSURES IN BLACK-AND-WHITE CHILDREN

The prevalence of hypertension is greater for blacks than whites. Whether black children have higher blood pressure than white children is less clear. We investigated this issue through a prospective longitudinal assessment of blood pressure in 345 white children and 164 black children. Each child had his or her blood pressure measured every 6 months for 2 to 5.5 years. The means for systolic and diastolic blood pressures for each individual were calculated, and the rate of change in blood pressure over time for each subject was estimated. The mean blood pressure and the mean rate were compared between gender-specific black and white groups. For both boys and girls, the mean systolic blood pressure was 2 mm Hg higher in black children than white children (P=.0008). Boys had a higher systolic blood pressure than girls (P=.0048). The mean diastolic blood pressure was 1.5 mm Hg higher in black children than in white children (P=.0270); no significant gender difference in diastolic blood pressure was observed. Age, weight, height, and body mass index were highly correlated with blood pressure. When accounting for these variables, for girls the racial difference in systolic blood pressure remained significant, whereas the difference in diastolic blood pressure in boys and girls was no longer significant. The rate of increase in blood pressure over time was significantly greater in blacks than whites: for systolic blood pressure, P=.0002, and for diastolic blood pressure, P=.009. There was no sex difference in rate of change in systolic blood pressure, whereas girls showed a greater increase in diastolic blood pressure over time than boys (P=.0131). In summary, the average blood pressure for black children was higher than in white children, and the blood pressure increased at a faster rate in blacks compared with whites. The findings suggest that mechanisms that predispose blacks to hypertension may be functioning in childhood.